Coloring or dyeing photographic images.



edge and belief, the silver verted into silver iodid by UNITED STATES PATENT OFFICE.

HOY'I. MILLER, 01? NEW YORK, N. Y., ASSIGNOR TO BREWSTER FILM CORPORATION, OR

NEWARK, NEW JERSEY, A co RPORATION OF NEW "OBK.

COLORING OR DYEING PHOTOGBAPHIG IMAGES 1 314,940. No Drawing.

To all whom it may concern:

Be it known that I, Hor'r MILLER, a citizen of the United States, at New York, in the county and State of New York, have invented certain new and useful Improvements in Coloring or Dyeing Photoraphic Images, of which the following is a ull, clear, and exact description.

This invention relates to the coloring or photographic images on cinematographic film, lantern slides, transparencies, paper rints, etc., and for use in color photograp y. Briefly stated, its chief object is to convert the black and white image into a colored image and to change the silver present into a transparent form which will not materially interfere with the passage of light or materially degrade or alter the color of the dyeymor other coloring matter used. To this and-other ends the invention consists in the novel features hereinafter described.

In practising the invention in the preferred manner, the object mentioned above is attained by treating the silver image with iodin in a solution of an iodid (preferably potassium iodid). To the best of my knowlso treated is conthe iodin andthe silver iodid so produced then converted or peptonized by the potassium iodid into a hydrosol or hydrogel of silver iodid, or silver iodid in a colloidal form; the gelatin (or other vehicle) of the emulsion acting as a dialyzing medium to hold the particles of the hydrosol or colloidal iodid in the positions occupied by the corresponding silver particles that made up the original image. The substance into which the silver of the original image is converted is highly transparent, and possesses the property of absorbing and holding dyes; and since the particles composing the same occupy the positions of the silver particles of the original dyeing of transparent) image ex- In short, the origiparticles are replaced by transparticles which are capable of 'aband holding dyes, so that when the Specification of Letters Patent.

Application filed February 26, 1915. Serial 0. 10,831.

Patented Feb. 6, 1917.

film is treated with tl 1e desired color or stain, as explained below, the original image is replaced by one consisting, at least in part, of the color used thereof with the substance of which the aforesaid transparent i1 iage was composed. Excess iodin or iodin st: in in the film is got rid of, or cleared, by a reducing agent, for example, sodium lisulfite; and after washing, the film or plate is treated with coloring matter of the desired tint, preferably an anilin dye, preferably but not necessarily basic. The strength of the dye solution and the duration of the treatment are not material, as excess of dye can be wasled out. The time for dyeing a good image with the dye lmown as malachite green in rat her strong solution may be less than thirty seconds. If the image is to be viewed only by reflected light, like a paper print, the dyeing or colorln materials used may be 01: aque or capable o giving'an opaque image but otherwise, if the image is to be viewed by transmitted lighter is to be exhibited by projection.

,After the above blea :hing and while the film is wet (but befoie dyeing) there is ordinarily no trace of the image observable, though if the original image were very strong or dense an image In relief can sometimes be seen. If dried without dyeing, a faint image of a yellowisl. color usually appears, but there seems to be no material impairment of transparency. The faint image referred to probably consists of colloidal silver iodid, or possibly traces ofx ordinary (yellow) silver iodid. K

In thedye treatment, basic dyes for the most part go chiefly into the image in proportion to the amount of s .lver in the original, leaving the high-lig hts colorless or nearly so. Usually a shortwash suflices to or some compound image, havin 'fire scenes, etc., or to secure a more If the film is exposed to strong light, the image can be redeveloped by most of the developing agents, for example metol. If the hydrosol image is warmed while wet, or if immersed too long in a reducing solution, the hydrosol may lose transparency, indicating (probably) conversion into ordinary silver iodid.

I prefer that the image before bleaching be without trace of fog, full of detail, thin, and quite soft, that is, devoid of harsh contrasts.

In practice, particularly in coloring films or plates for use in subtractive processes of color photography or cinematography, where it is desirable that the color-images be as little as possible degraded with residual black or other colored images, I proceed preferably as followsi The film bearing the image is first hardened in a ten er cent. solution of formalin or other suita 1e, bath, then washed for a few minutes, and then bleached, by spraying or immersion, with a bath consisting of, say, iodin .1 (onetenth) gram, potassium iodid 5 grams, and water to make 100 cc.. This treatment is continued .until. the original image disapears and is replaced by a vague or faint stained with lodin, one to ten minutes. The film is then washed and treated-with a one to two per cent. solution of sodium bisulfite or other reducing agent to remove the excess iodin or iodin stain, after which the film is washed to get rid of the reducing agent. The film should now be perfectly transparent with no image perceptible, except original image were rather heavy. The film is then s rayed with or immersed in an aqueous dye ath, for example of malachite green or xylene red. The strength. of the d e bath is immaterial. It may be very wea or it ma be a saturated solution. The time of treatment is also variable, depending, aplparently, upon the strength of the dye bat and the amount of silver in the ori image, and may last from a few secon to an hour. After thorough washing to suitably clear the high lights the film can be dried.

If the bleaching bath be acidified I prefer it to be approximately as follows: iodin 1 to 5.grams, potassium iodid 50 grams, acetic acid (three per cent. solution) 50 to 150 cc., water 1000 cc., depending on therapidity of action If it is desired to color or tone mono chromatic images on paper, plates, or cinematographic film, to represent night scenes, pleasing than black and white, as for it is sometimes desirable to or warmer tone example, sepia,

its. high lights more or less which usually takes from in slight relief ifthe of the have a slightly stronger transparent residual image, in order to give the picture body or depth; in which case I may use a bleach of the following general type: potassium iodid 5 grams, acetic acid (three per cent. solution) 10 to 50 cc., potassium bichromate (one per cent. solution) 5 cc., water to make 100 cc. This bleaches the images rapidly and leaves the desired slight residual transparent yellow image. a Another excellent bleach, apparently producing its free'iodin by the reaction of two or more of its ingredients, is composed of potassium iodid, acetic acid and potassium bichromate, say in about the proportion of 5 grams of the'iodid, 5 cc. to 25 cc. of'the acid (three per cent; solution), bichromate (one. per cent. solution) 5 cc. to 25 cc., and water to make 100 cc.

Instead of a haloid salt the silver can be converted into a ferricyanid, as these salts in the form of a hydrosol or hydrogel are capable of acting as mordants for certain dyes or coloring matter. In lieu of iodin in the bleaching process chlorin or bromin (and theoretically fluorin) can be used, the potassium iodid being preferably replaced by the correspondchromate, ferrocyanid or p ing chlorid or bromid, or fluorid, as the case may be, I i

he acetic acid in the bleach can be replaced by hydriodic,

nitric. or formic acid, or by any other acid that does not have a harmful effect on the bleaching reaction or reagents being (apparently) to release iodm' from the potassium iodid. 'In short, I believe the leach should. contain a reagent adapted to convert the silver into a salt of silver (preferably a haloid salt) andone to convert the salt mto a hydrosol, or adsorption compound, thereof.

The action of the first mentioned bleaching bath is accelerated by the addition of an oxidizing agent, as for example potassiumbichromate. If by reaoriginal image. being overly dense orheavy the residual image is too'strong for the. purpgse in general, overcome by acidifying the bath or increasing the amount of acid therein. It has been observedthat if the bleached film be dyed without beingpermitted to dry first, any residual image thatthe same may have had disappears or becomes less noticeable after dyein and seems to have but little degrading e ect on the color"; whereas if the film with a considerable resldual image in hand the difliculty can,

or boosted b the addition of free iodin in alcohol, and't e others be dried first, the color of the image produced by dyeing is apt to be materially degraded.

The temperature of the various steps in the process is not important, except that at temperatures approximating 100 F. the transparent image (if Wet) may become more or less opaque, probably by reversion of transparent hydrosol to opaque iodid, as stated above. This is in general disadvantageous if the image is to be viewed by transmitted light or exhibited by projection. For such purposes a temperature around 70 F. gives results that are eminently satisfactory.

Among the numerous dyes usable I may mention pyronin, acridin red B, xylene red, aeridin orange, malachite green, thionin blue, methylene blue, auramin, methylene yellow, rhodamin, magenta, and methyl violet. In fact I have not found any basic anilin dye that is wholly unsatisfactory.

My belief that the silver is converted, at least in part, into a hydrosol, or a hydrogel finds confirmation in the Work of Bancroft, Lottermoser, and Wall. See, for example, Journal of Physical Chemistry (Ithaca, N. Y. vol. 14, and Journal Pralctisclw Ghem'z'c (Leipzig), vol. 68, pp. 341-343, vol. 72,.pp. 3941, vol. 73, pp. 374-382.

It is to be understood that the invention is not; limited to the precise materials and proportions given herein, but can be practised in other ways without departure from its spirit.

I claim:

1. The herein described method, comprising converting the silver of a photographic image into a transparent dye-absorptive substance, and treating the same with a dye fof the desired color.

2. The herein described method, comprising converting the silver of a photographic .mage into a transparent adsorption compound of silver, and treating the same with t dye of the desired color.

3. The herein described method, comprisng treating the silver of a photographic mage with a halogen and a halogen salt, .nd treating the same with a dye of the deired color.

4. The herein described method, comprisng treating the silver of a photographic nage with a halogen and an iodid, and reating the same with a dye of the desired )lor.

5. The herein described method, compris- 1g converting the silver of a photographic nage into a hydrosol or hydrogel of a haloan compound of silver, and treating the -.me with a dye of the desired color.

6. The herein described method, comprisg converting a photographic silver-image into an image com posed of a. hydrosol or hydrogel of silver iodid, and treating the same with a dye'of the desired color.

7. The herein the zribed method, comprising treating the silver of a photographic image with iodin in the presence ofpotassium iodid, and trea ;ing the same with a dye of the desired color. 1

8. The herein deszribed method,comprising treating the siwver of a photographic image with a bath :ontaining an iodid, an acid, and an oxidizi11 agent, whereby iodin is set free until t e image is suitably bleached, and treati 1g the same With a dye of the desired color.

9. The herein described method, compris ing treating the silver of a photographic image with iodin in the presence of a substance capable of con vrting silver iodid into a hydrosol or adsorp tion compound thereof, treating the image with a reducing agent, and treating the im age with adye of the desired color.

10. The herein des :ribed method, comprising bleaching a photographic image by treatment with iodir and an iodid, treating the bleached image with sodium bisulfite to clear the same of iodin, washing out the bisulfite, treating the image with a dye of the desired color, anl then washing out the excess dye.

11. The herein des :ribed method, compris ing bleaching the im: Lge with a solution contaming potassium i lid, an acid, andipotassium bichromate whereby iodin is set free; washing the bleached image; treatirfg the washed image with sodium bisulfite to; ear the same of iodin; washing the cleared image; treating the cleared and washed image with a dye of the desired @101, and washing the dyed image to clear it of excess dye.

12. The herein desr ribed method, comprising hardening the emulsion which carries the silver composing she image by treatment with a suitable hart ening agent; treating the image with a solution containing potassium iodid, acetic a( id, and potassium bichromate, whereby ic din is set free and the image is bleached; washing the bleached image; treating the washed image with sodium bisulfite to clear the same; washing the cleared image; tr eating the cleared and washed image with a dye of the desired color; and washing the dyed image.

13. The herein (lescribed method of bleaching a photographic image, compris ing treating the silv er of the image with substances capable of converting the same into an adsorption compound of a silver salt.

14. The herein described method of bleaching a photographic image, comprising converting the silver of the image into an adsorption compound or hydrosol of a silver salt.

15. The herein described method of bleaching a photographic image, which con- .sists in treating the silver of the image with a halogen and a haloid salt.

16. A photograph having an image composed chiefly of a colored hydrosol or hydrogel of a salt of silver.

17. A photograph having an image composed chiefly of a colored hydrosol or hydrogel of a silver haloid.

HOYT MILLER.

Vitnesses H. T. OLIVER, E. G. MEYER. 

